Understanding the role and significance of the Arctic for the cycling and fate of persistent organic pollutants (ARCPOP)

2006年6月15日，世界野生动物联合会（WWF）发布了一份名为《温柔地杀死它们》的报告，其中强调了对北极野生动物，特别是北极熊等海洋哺乳动物体内持久性有机污染物积累和毒性影响的关注。《泰晤士报》刊登了一篇整版文章总结了这份报告，并详细介绍了滴滴涕和多氯联苯（PCB）等“遗留”化学品，以及溴化阻燃剂和全氟表面活性剂等“新”化学污染物的增加，这些污染物也在北极动物群中积累，并增加了额外的毒性风险。这些污染物的高含量使像北极熊这样的动物在恶劣的北极条件下生存和应对气候变化影响的能力下降。本提案中的工作旨在研究这些化学品是如何进入北冰洋表面沃茨的，从而进入海洋食物网的基础。持久性有机污染物通过远距离迁移到达北极，主要是通过来自欧洲、北美和亚洲来源区域的空气，但也通过表层洋流。北极的寒冷条件有助于促进这些化学物质在雪和表面沃茨中的积累，并减缓任何分解和蒸发损失。然而，人们对从大气中去除这些污染物，将其储存在冰雪中，然后将其转移到北冰洋的过程知之甚少，然而这些过程可能因所讨论的化学物质而异。例如，有些化学品相当易挥发（即它们有蒸发的趋势），因此，虽然它们可以到达北极并随着降雪沉积，但由于它们在北极夏季的大气中流失，它们不太可能到达海洋。另一方面，较重、挥发性较低的化学品与雪和颗粒物紧密结合，并可在夏季融化期间进入海水。气候变化和全球变暖正在改变北极，并影响污染物的路径。例如，冰导（海冰上的大裂缝，导致海水“湖泊”）的数量正在增加。因此，化学污染物到达海洋沃茨的路径正在发生变化，实际上可能会缩短，对海洋野生动物构成更大的威胁。在无冰期，海洋表面水与大气接触（而不是被海冰覆盖），空气中的污染物可以直接溶解到寒冷的表面沃茨中。令人鼓舞的是，有证据表明北极大气中的一些“遗留”污染物正在减少，但许多“现代”化学物质实际上在北极生物群中正在增加，需要努力测量它们的输入并了解它们在这种不寻常的环境中的行为。例如，在极地日出（24小时日光）后阳光照射的表面雪中，这些化合物中的一些可以通过吸收阳光而降解，并且在某些情况下，这可以产生随后进入食物链的更稳定的化合物。因此，降雪沉积的化学污染物的数量和化学品在融雪过程中的命运是重要的过程，以解决，特别是了解这些污染物对海洋生态系统的负荷和影响。该项目旨在了解这些过程，并了解哪种类型的污染物及其数量对野生动物构成最大威胁。

On June 15 2006, the World Wildlife Federation (WWF) released a report called 'Killing them Softly', which highlighted concern over the accumulation and toxic effects of persistent organic pollutants present in Arctic wildlife, particularly marine mammals such as the Polar Bear. The Times newspaper ran a full-page article summarising this report and detailed 'legacy' chemicals such as DDT and polychlorinated biphenyls (PCBs), as well as the rise in 'new' chemical contaminants such as brominated flame retardents and perfluorinated surfactants, which are also accumulating in arctic fauna and adding an additional toxic risk. The high levels of these contaminants are making animals like the Polar Bear less capable of surviving the harsh Arctic conditions and dealing with the impacts of climate change. The work in this proposal intends to examine how these chemicals are delivered to surface waters of the Arctic Ocean, and hence the base of the marine foodweb. Persistent organic pollutants reach the Arctic via long-range transport, primarily through the air from source regions in Europe, North America and Asia, but also with surface ocean currents. The cold conditions of the Arctic help to promote the accumulation of these chemicals in snow and surface waters and slows any breakdown and evaporative loss. However, the processes that remove these pollutants from the atmosphere, store them in snow and ice and then transfer them to the Arctic Ocean are poorly understood, and yet these processes may differ depending on the chemcial in question. For example, some chemicals are rather volatile (i.e. they have a tendency to evaporate), so while they can reach the Arctic and be deposited with snowfall they are unlikely to reach the ocean due to ltheir oss back to the atmosphere during the arctic summer. On the other hand, heavier, less volatile chemicals, become strongly bound to snow and particles and can be delivered to seawater during summer melt. Climate change and a warmer world are altering the Arctic and affecting pollutant pathways. For example, the number of ice-leads (large cracks in the sea-ice that give rise to 'lakes' of seawater) are increasing. As a result, the pathways that chemical pollutants take to reach ocean waters are changing and may actually be made shorter, posing an even greater threat to marine wildlife. During ice-free periods, the ocean surface water is in contact with the atmosphere (rather than capped with sea-ice) and airborne pollutants can dissolve directly into cold surface waters. Encouragingly, there is evidence that some of the 'legacy' pollutants are declining in the arctic atmosphere, but many 'modern' chemicals are actually increasing in arctic biota and work is required to measure their input and understand their behaviour in this unusual environment. For example, in sunlit surface snow following polar sunrise (24 h daylight), some of these compounds can degrade by absorbing the sunlight, and in some cases, this can give rise to more stable compounds that subsequently enter the foodchain. Therefore, the quantity of chemical pollutant that is deposited with snowfall and the chemical's fate during snowmelt are important processes to address, especially to understand the loading and impact of these pollutants on the marine ecosystem. This project aims to understand these processes, and to understand which type of pollutants and their quantities pose the greatest threat to wildlife.